The vertical-cavity surface-emitting lasers (VCSELs) with high single-mode (narrow linewidth) output power are essential to minimize chromatic dispersion and to further improve the bit-rate distance product in a multimode fiber, which has a significant propagation loss (∼3.5 dB/km) at 850 nm wavelength. Here, we demonstrate the detailed design considerations and fabrication of a single-mode, high-power, and high-speed VCSELs at the 850 nm wavelength with oxide-relief and Zn-diffusion apertures for the application of short (0.3 km) to medium reach (2 km) optical interconnects. By optimizing the relative geometric sizes between two such apertures in our demonstrated 850-nm VCSELs, we can not only attain high single-mode output power (∼6.5 mW), but also with a reasonable threshold current (< 2.0 mA). Furthermore, the spatial hole burning effect induced low-frequency roll off can also be minimized in our optimized structure to obtain a maximum data rate up to 26 Gbit/s. The record-high bit rate-distance products for OM4 MMF transmission under ON-OFF keying (14 Gbit/s × 2.0 km) modulation formats have been successfully demonstrated by the use of our VCSEL.
In order to investigate the tradeoff between optical spectral width and modulation speed of 850-nm Zn-diffusion vertical-cavity surface-emitting laser (VCSEL) and its influence on the performance of discrete multitone (DMT) modulation, two kinds of high-speed VCSEL structures with different cavity lengths (λ/2 and 3λ/2) are studied. By shortening the cavity length to λ/2, allocating the oxide layer in the standing-wave peak, and performing a Zn-diffusion aperture in our VCSEL structure, stable dual mode in the output optical spectra across the full range of bias currents with good high-speed performance (∼16-GHz bandwidth) can be achieved. Compared with its multimode reference, it shows far less roll-off with regard to the maximum data rate versus transmission distance over OM4 multimode fibers under forward error correction (FEC) threshold (BER< 3.8 × 10 −3 ). On the other hand, for the 3λ/2 VCSEL structure, by using the same Zn-diffusion conditions as those of dual-mode counterpart, highly single-mode operation (side-mode suppression ratio> 35 dB) with high available power can be achieved over the full range of bias currents. Although such device shows a smaller 3-dB electrical-tooptical bandwidth (12 versus 16 GHz) than that of the dual-mode one, it exhibits a superior transmission performance by use of DMT modulation format. A record high bit-rate distance product (107.6 Gb/s·km) at nearly 50-Gb/s transmission under FEC threshold (BER< 3.8 × 10 −3 ) through 2.2-km OM4 fibers has been successfully demonstrated by the use of single-mode VCSEL with optimized structures. In addition, error-free (BER< 1 × 10 −12 ) Communications as a Task Leader and then been promoted to a Project Leader in 1992. In 1998, he left CHTL and founded LandMark Optoelectronics Corporation (LMOC) producing InP-and GaAs-based epiwafers by MOVPE technology. LMOC's epiwafers are mainly applied to optical fiber communications. He was the Vice President in LMOC during 1998 to 2005 and has been promoted to the General Manager since 2005. He has also been the Leader of the Research and Developing Group in LandMark since 2011. He has been working on metalorganic vapor phase epitaxy (MOVPE) for 23 years. His research interests include growth and characterization of III-V compound semiconductors, fabrication and characterization of modulation-doped pseudomorphic Al-GaInAs/(In)GaAs or AlGaAs/(In)GaAs FET's, many kinds of InGaAsP//InP or AlGaInAs/InP long-wavelength lasers (1.2-1.9 m), InGaAs/InP photodetectors and GaAs-based material high-power lasers and vertical-cavity surface-emitting laser.
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